Section 230 of the ironically-named 1996 "Communications Decency Act" provides that:  "No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider" (47 U.S.C. § 230).   What this means is that, whereas the New York Times is liable in tort if it publishes a letter that defames you or intentionally causes you emotional distress, if the exact same statement appears on Twitter, Twitter is not liable, only the author of the letter is.  (The author of the letter is liable in both contexts, of course.)  

The provision was meant to encourage the development of the Internet, which it has, and it is also primarily responsible for the Internet being the cesspool of misinformation, abuse, and tortious wrongdoing that it is.   Although Twitter polices speech on its platform in arbitrary ways, it–like most social media platforms–claims it would be impossible to actually police the platform for unlawful speech.   Note the further irony that Twitter, as things stand, is legally responsible for copyright violations by its users, and has established procedures for remedying such violations (these rules also impose burdens and costs on those claiming copyright violations).  Why Twitter and other social media platforms should get a pass on tortious wrongdoing by their users but not on violations of copyright by their users is a bit puzzling, shall we say.

Trump is too stupid to realize that if section 230 is repealed, then Twitter will be sued for all his libel and infliction of emotional distress, and rather than run that risk, they will delete his account in a second flat.  So let us hope he gets his way!

I have long favored either repeal or at least substantial modification of Section 230.  I discussed the matter in some detail in "Cleaning Cyber-Cesspools:  Google and Free Speech," in S. Levmore & M. Nussbaum (eds.), The Offensive Internet (Harvard University Press, 2010); I was never able to put it online (because of copyright rules imposed by Harvard U Press!), but if you want a copy, e-mail me and I'll send it to you.